Anyone who has observed recent developments in Germany, and to a growing extent in Australia, will have noted the rapidly changing dynamics of electricity markets caused by the growth in renewables. So much so, that according to this graph of the day, the concept of baseload power may be redundant in Germany within a decade.

The graph of the day shows how Germany’s electricity market might look like in 2022, in a week of August, when windy and sunny weather help wind farms and solar plants deliver most of the electricity requirements, needing little extra from fossil fuel plants (nuclear power has already been closed). On the other days, however, there is less wind and solar, so more fossil fuel is required.

What does this mean for baseload power stations? The irony is that while “intermittent sources” such as wind and solar are criticised now for being unsuitable for our energy market needs, in the future it will be the “base load” generators which will be unsuitable for our energy market needs.

That’s because they will get squeezed out of the market. The gaps in the energy market will need to be filled by flexible generators. The leading germany utilities have already recognised this. The most recent new coal fired plants are designed for such flexibility, able to ramp up and down 500MW in less than half an hour. Gas, though, is the preferred source over coal. In sunny countries, it will likely be solar thermal with storage. Elsewhere, it will be hydro.

This is a complete change from the past, where baseload power trundles throught the night and day and is augmented by “peaking” power, usually expensive fast response gas generation, when demand increases.

According to the report by Agora Energiewende, by 2022 there will be enough wind, solar and other renewable generation in Germany to cover total load (base, mid- and peak- load) during many hours throughout the year, as shown in the graph of the day.

It notes that power plants must be rapidly ramped up and down over short periods of time in order to compensate for these fluctuations. As the share of wind and solar power increases, this will also apply to the few remaining “base-load power plants”. In the future, all remaining fossil fuel power plants will need to operate on a flexible basis.

This is exactly what UNSW researchers Mark Diesendorf, Ben Elliston and Iain McGill predicted in their scenarios for 100 per cent renewable energy for Australia, and David Mills concluded in his scenario in the US. Their scenarios were divided between inflexible and flexible generation, or renewables and dispatchable generation.

Time will tell whether dispatchable generation, particularly in solar rich nations such as Australia, will ultimately be delivered by gas, or technologies such as solar thermal with storage – as well as existing hydro. The authors at Agora Energiewende say wind power and solar will form the basis of a future, low-carbon energy system in many countries, and will face similar challenges that Germany is facing today.

In the meantime, to achieve that transition in the most cost effective way, German policy makers are looking for ways to redefine energy markets. The traditional means of paying per kilowatt hour, which more or less protected the incumbent industry, now seems redundant because wind and solar have no fuel costs.

Capacity markets, where plants get payments for existing, are not the solution either – so work in now being done on the development of “capabilities markets” which reflects the value of energy provided, in economic, availability and environmental terms. As the Agora report notes: “The challenge is not about technology and control, but rather about incentives.”

For a fully renewables grid, those yellow “bumps” of solar output would need to be at least twice the height. The performance of the storage system or other flexible generation which does the demand balancing will need to be phenomenal. For Germany it will need to be able to match solar ramp rates of possibly 30 GW/h or 500 MW per minute! I think this is doable but it will be very difficult.

Mart

The Germans seem to be working quite confidently on their power-to-gas solution.

Fwiw

Totally backwards. The challenge is engineering the capabilities and controls. 500 mw per minute is normal on an exchange the size of Germany’s.

David

So you think starting up the equivalent of a large gas turbine every minute for two hours is normal? That is adding one Newport power station every minute for two hours.

David

For anyone still reading this old thread, I wanted to point out how Fwiw misunderstands the scale of this problem.

Any grid which is large enough to have a 500 MW generator can cope with its instantaneous loss. That means it must have spinning reserve greater than 500 MW. However it cannot cope with successive losses of 500 MW generators at 1 minute intervals which goes on for hours.

Germany has an average demand of roughly 50 GW. If it was fully solar and wind based with 50 % solar, then that is 25 GW average from solar. At a power factor of (no better than) 20%, this would require 125 GW of solar and very efficient storage.
On a given day you may have a demand minimum of 40 GW at 6am and max of 60 GW at noon. Solar output would be very little at 8am and nearing its maximum at 10 am. Thus we go from non-solar generation of approximately 40 GW at 8am to storing nearly 65 GW at 10am. If that initial 40 GW was wind, then it also should be stored (even worse if the wind generation is closer to its rated output of say 75 GW). That is a swing of at least 100 GW in about 2 hours.
I don’t know how Fwiw can trivialise the scale of this immense challenge.

Dimitar Mirchev

According to Germany TSOs in 2017 they will have at least 50 GWp:

In 2017 the TSO expect an installed capacity of renewable energy sources of 111,358 MW, up almost 28% from the expected 80,622 MW at the end of 2013. Solar power and wind power are believed to account for 91% in 2017 (solar: 54,838 MW, wind onshore: 38,747 MW, wind offshore: 7,853 MW).

South Australia now has no baseload power plants with its only coal plant not in mothballs operating in seasonal load following mode. It will be interesting to see what happens in other states as time progresses.